Organoboron emitters with narrowband thermally activated delayed fluorescence for doped organic light emitting diodes

Abstract

Thermally activated delayed fluorescence (TADF) materials with narrowband emission are highly desirable for ultrahigh resolution displays with organic light emitting diodes (OLEDs). In this study, we report a novel organoboron molecule (S-BNBP) consisting of an organoboron core unit with two β-styryl groups as end-capping units. S-BNBP exhibits a high photoluminescence quantum yield (PLQY) of 67% and a narrowband chartreuse fluorescence with a full width at half maximum (FWHM) of 30 nm in solution. Tunable photophysical properties are demonstrated from the solution to the crystalline state. Moreover, S-BNBP in the doped film exhibits host–guest TADF characteristics with a PLQY of 18% and emits a narrowband yellow fluorescence with a FWHM of as small as 35 nm and a short lifetime of 155 ns. The doped OLEDs based on the S-BNBP:CBP films achieved an external quantum efficiency (EQE) of 2.81%, CIE coordinates of (0.58, 0.41), and a narrowband FWHM of 42 nm. These results indicate that the organoboron molecule S-BNBP is a promising candidate for narrowband fluorescent emitters for OLEDs.